[
https://issues.apache.org/jira/browse/HIVE-21686?focusedWorklogId=241288&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-241288
]
ASF GitHub Bot logged work on HIVE-21686:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/May/19 20:46
Start Date: 13/May/19 20:46
Worklog Time Spent: 10m
Work Description: odraese commented on pull request #626: [HIVE-21686]
ensure that memory allocator does not evict using brute …
URL: https://github.com/apache/hive/pull/626#discussion_r283525719
##########
File path:
llap-server/src/java/org/apache/hadoop/hive/llap/cache/LowLevelCacheMemoryManager.java
##########
@@ -66,6 +66,21 @@ public void reserveMemory(final long memoryToReserve,
AtomicBoolean isStopped) {
throw new ReserveFailedException(isStopped);
}
+ /**
+ * Ask the memory manager to evict more memory
+ *
+ * @param memoryToReserve amount of bytes to evict
+ * @return actual amount of evicted bytes.
+ */
+ @Override public long evictMemory(long memoryToReserve) {
Review comment:
memoryToReserve -> memoryToEvict?
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
Issue Time Tracking
-------------------
Worklog Id: (was: 241288)
Time Spent: 1h (was: 50m)
> Brute Force eviction can lead to a random uncontrolled eviction pattern.
> ------------------------------------------------------------------------
>
> Key: HIVE-21686
> URL: https://issues.apache.org/jira/browse/HIVE-21686
> Project: Hive
> Issue Type: Bug
> Reporter: slim bouguerra
> Assignee: slim bouguerra
> Priority: Major
> Labels: pull-request-available
> Attachments: Cache_hitrate_improvement.csv, HIVE-21686.2.patch,
> HIVE-21686.patch
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> Current logic used by brute force eviction can lead to a perpetual random
> eviction pattern.
> For instance if the cache build a small pocket of free memory where the total
> size is greater than incoming allocation request, the allocator will randomly
> evict block that fits a particular size.
> This can happen over and over therefore all the eviction will be random.
> In Addition this random eviction will lead a leak in the linked list
> maintained by the policy since it does not know anymore about what is evicted
> and what not.
> The improvement of this patch is very substantial to TPC-DS benchmark. I
> have tested it with 10TB scale 9 llap nodes and 32GB cache size per node.
> The patch has showed very noticeable difference in the Hit rate for raw
> number [^Cache_hitrate_improvement.csv]
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
